The so-called still video floppy disc system is known as an apparatus for recording and reproducing still pictures (see "Nikkei Electronics," July 2, 1984, pp. 80-85, published by Nikkei McGraw-Hill).
FIG. 17 shows a magnetic disc pack 1 for the still video floppy disc system. The pack comprises a flat rigid jacket 11, and a magnetic disc 12 rotatably housed in the jacket 11. The magnetic disc is usable for recording 50 still pictures (in the case of field recording).
Such magnetic disc: packs are usable to provide an image filing system. For example, a multiplicity of still pictures can be filed if it is possible to provide an apparatus comprising a boxlike pack holder 2 for holding magnetic disc packs 1 therein as seen in FIG. 5, and an automatic mechanism for withdrawing the desired pack 1 from the holder, transporting the pack to a specified signal recording-reproduction position and returning the pack to the holder after recording or reproduction. If the apparatus is adapted for automatic pack changing, for example, for 10 magnetic disc packs, a filing system can be realized for recording or reproducing 500 images.
Unexamined Japanese Patent Publication SHO 61-267966 discloses an automatic magnetic disc: pack changing apparatus which is usable for such a filing system. FIG. 19 shows the disclosed apparatus. After a pack holder 2 is loaded into the apparatus with magnetic disc packs 1 accommodated therein, the pack holder 2 is moved in the direction of arrow A to bring the pack 1 to be used for recording or reproduction to a position opposed to a bucket 9 in a standby position. The pack 1 is then transported in the direction of arrow B and loaded into the bucket 9 by the pack transport mechanism to be described below. The bucket 9 is thereafter moved in the direction of arrow C along with the pack 1 to mount the pack 1 on a rotary drive shaft 91. The magnetic disc in the pack 1 is then driven by the shaft to record or reproduce signals. When to be changed for another pack, the pack is transported reversely.
With reference to FIG. 20, the pack transport mechanism comprises a pawl 92 engageable in a recess 17 formed in the jacket of the pack, and reciprocating means 93 connected to the pawl.
With the above automatic pack changing apparatus, the magnetic disc: pack 1 must be transported first in the direction of arrow B and then in the direction of arrow C perpendicular to the direction B as seen in FIG. 19. Accordingly the transport of the pack requires a complex mechanism, while the change of the pack requires a period of time since the pack needs to be transported a large distance with a change of its course. Moreover, changing the course of transport renders the pack very prone to damage.
Additionally, the transport mechanism is in direct engagement with the disc pack 1 as shown in FIG. 20, so that the accuracy with which the pack is positioned in place is dependent on the accuracy of positioning the transport mechanism. Since the pack transport mechanism is complex as stated above, it is difficult to set the pack in the specified recording reproduction position accurately.